Electrodeposition of uranium



Feb. 12, 1957 H. A. WILHELM ETAL 2,781,304

ELECTRODEPOSII'ION OF URANIUM Filed Aug. 15, 1946 Jana Id .flkzzazz 7a nnn'crnonnrosmon'on maa uiwimasndbalsa assignors to the United States of America as represented by the; .Unitedtstates Atomic Energy. Commission This invention relates to the electrodeposition of uranium in metallic form. More particularly, this invention is concerned with a process for electroplating uranium metal from a salt bathcontaining a uranium halide such as uranium tetrahalide.

Prior to the present invention it has been proposed to electrodeposit uranium from certain fused baths containing a uranium salt such as KUFs. Uranium in such ba'ths must be replenished by addition of further portions of the uranium salt during the electrodeposition process.

In accordance with the present invention it has been discovered that uranium carbide may be subjected to anodic treatment in a fused halide bath with consequent dissolution of uranium in the bath and uranium electrodeposited in metallic state from the resulting bath. By

this means the electrodeposition process may be conducted without the necessity of replenishing the KUFs or other uranium salt undergoing electrolysis.

The electrolysis may be conducted using uranium carbide as the anode if desired. Alternatively, it has been found that the process may be conducted using the electrolytic cell, which may be constructed of graphite or an inert metal such as tungsten or other inert material and cathodes of suitable material such as stainless steel, iron, tantalum, copper, graphite or uranium. In such a case, the uranium carbide is placed in contact or at least closely adjacent to the anode whereby the uranium carbide is anodically broken down and uranium dissolved either-by direct electrolytic action or by action of the evolved halogen. 1

Various types of electroplating apparatus of conventional design will be found suitable for use in the process of the present invention. The accompanying drawings illustrate two specific types of apparatus in which:

Fig. l is a diagrammatic vertical sectional view of a type of cell which may be used in the present process; and

Fig. 2 is a diagrammatic vertical sectional view of a modified type of cell suitable for such use.

Fig. 1 consists of a suitable cylindrical crucible of graphite or similar inert material containing the melt 12 to be electrolyzed, the crucible 10 being the anode. The sides of the crucible 10 are shielded by a quartz sleeve 14 which limits flow of current to the cell bottom. A cathode designated by the reference numeral 16 may be made from any suitable'material such as stainless steel and is suspended centrally in the electrolyte 12 as is shown most clearly in Fig.1. Uranium carbide which has been designated generally by the reference numeral 18 is placed in the bottom of the crucible 10. Rods22 are connected to a source of-direct current 26, the circuit being closed by means of switch 24. Suitable means (not shown) may be provided for heating the cell and maintaining the electrolyte molten if desired.

The apparatus shown in Fig. 2 illustrates a sectional view of a modified electrolytic cell consisting of a suitable cylindrical crucible 10 containing the melt to be electrolyzed, the crucible 10 being the anode. A perforated 9 of switch ,24.

it d S s Pat i 2,781,304 we e b- 1 sillimanite diaphrag ni zo shields the sides of the crucible 1i) and holds 'the uranium carbide'18 to'the sidesof the crucible ,10. A cathode designated by the reference mear 16 'may be made from stainless steel or other suitableimaterial and issuspended centrally in the electrolyte 12 as i s 'shown most clearly in Fig.2.' Uranium carbide 18 is packed in the bottomof the crucible 10'and between the perforated" diaphragm 20 and theside walls of; the c'itidible" 101" j Leads 2} are I connected to a source of direct currenfzi'thecircuit being closed 'by means ""The' temperatures to be employed in carrying out' the proces's'of this invention fmayivaryf rather widelyyand substantially any temperature atwhich the particular bath material is in a molten state may, in general, be considered satisfactory. Satisfactory temperatures which have been successfully employed have ranged between about 500 C. and 850 C. The metallic uranium may be deposited on a suitable cathode such, as for example, one made from graphite or stainless steel at voltages in the range of about 1 to 30 volts and current densities between about 0.1 and 5 amperes per square centimeter. It is advantageous to carry out the electrodeposition in an inert atmosphere or in vacuo in order to avoid oxidation of the resulting deposited metal.

The electrolyte utilized in this invention may be composed largely of a fused uranium salt such as KUFs or fused mixtures of alkali metal or alkaline earth metal halides and uranium halide such, as for example, potassium bromide, sodium bromide, calcium chloride, sodium chloride, potassium chloride or mixtures of calcium chloride and sodium or potassium chloride and uranium tetrabrornide. Equimolar mixtures of an alkali metal halide such as sodium or potassium chloride and an alkaline earth metal halide such as calcium chloride are suitable. The concentration of uranium in such an electrolyte depends upon the nature of the electrolyte and the rate of deposition and anodic solution of the uranium and usually is small, rarely being in excess of l10 weight percent of the electrolyte.

The reaction appears to proceed in accordance with the following equation:

where X is halogen and n is a small number designating the atomic ratio of carbon to uranium. Various carbides or carbon-uranium mixtures ranging in composition from UC to UC1]. may be used for this purpose.

The process of the present invention may be further illustrated by the specific example given below. The electrolysis set forth in this example was carried out in the apparatus shown in Fig. 1 using a graphite crucible as an anode and a stainless steel electrode.

Example grams of uranium carbide were crushed and placed in the bottom of the graphite crucible. About 5 grams of uranium tetrafluoride were mixed with 337 grams of calcium chloride and 163 grams of sodium chloride. The mixture was heated in the graphite crucible to about 800 C. A stainless steel cathode was positioned in the melt and an E. M. F. of about 4 volts was applied for about 2% hours. The current density was about 0.4 ampere per square centimeter. About 1 gram of uranium was deposited on the cathode and uranium tetrachloride was formed from the uranium carbide.

Although the present invention has been described with reference to specific details of certain embodiments thereof, it is not intended that such details shall be regarded as limitations except insofar as included in the accompanying claims.

What is claimed is:

1. The process which comprises electrodepositing uraar wm nium t a a f e bat con ain anium helm? an in the presence of uranium carbide.

2. The process which comprises electrodepositing uranium from a fused bath containing uranium halide an amallcaline earthmetal halide Vin the presence of uranium carbide; V I

3. The process which comprises electrode ppsiting uranium from mused bath containing uranium halide and an alkali metal halide in the presenceof l ranium carbide. r V l i 4. A continuous process for electrodepositing uraniun which comprises conducting the electrolysis from a bath containing auranium halide'and sodium chloride in the presence of uranium carbide. a

5. A process of forming a uranium salt which cornprisesisubjecti ng uraniufil carbide; to anodic treatment in a iused light metal halide bath.

6e Accnti process for electm spns t an u which compri s conducting the electrolysis from a bath containing uranium tetrafluoride in the presence of uranium carbide.

7. A continuous process for electrodepositiug uranium, which comprises subjecting an electrolysis bath containing a uranium halide and a halide of 'light metal maintained between 590 and800 Q. to a voltage of 1130 volts 1 and a current density of 0. l5 am eres/cm. in the pres;

ence of uranium carbide. I I H References Cited in the file of this patent Van Liempt, Z, fiur Elektrochern, vol.; .31, pp. 249 and 250 (1925). V

Driggs et 211;:

Ind. & Eng. Chem; v01. 22, pp. 516 and 517, (19350) 

1. THE PROCESS WHICH COMPRISES ELECTRODEPOSITING URANIUM FROM A FUSED BATH CONTAINING URANIUM HALIDE AND IN THE PRESENCE OF URANIUM CARBIDE. 